As you Shelfari users know, sometime in the next couple weeks (I've seen several dates mentioned, but March 16th seems to be the most popular) Amazon.com will shut down your site and merge you and your library with that den of iniquity known as Goodreads. Fortunately Library Thing is coming to the rescue, at least in offering a new home for your online library:
"Now you can import your Shelfari library, and receive an automatic upgrade to a free lifetime LibraryThing account! Here’s how to do it:
Export Your Shelfari Data
You’ve got a couple options when it comes to exporting your Shelfari library, and can either directly download a file, or have one emailed to you. See Shelfari’s instructions here.
Sign Up for LibraryThing
It’s quick and free! Head over to LibraryThing.com and click “Join Now.” Enter your desired username and password (we also recommend including your email address, for password resetting purposes), and you’re good to go!
If you’ve already got a LibraryThing account, you can import your Shelfari library to your existing account.
Import Your Shelfari File to LibraryThing
Once you have your Shelfari export file, go to our Shelfari Import page and upload it there."
I have been a member of Library Thing since 2005, and I think they are marvelous. That said, if you'd rather keep your online library on a site that posts reviews for books I've never written, I understand completely. In fact I encourage you to stay away from Library Thing. We're not your sort, really.
For more information and all applicable linkage on how to save your Shelfari from Goodreads, go to Library Thing's blog post here.